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A^bent tube, which passes through one hole, connects the flask
with a condenser and receiver. A tap-funnel is inserted through
the other hole. The flask is placed upon a sand-bath, and the
receiver is cooled in ice. It is important that all the corks
should be tight, as a small leak will considerably diminish the
yield. The potassium bichromate in small pieces and the
420 c.c. of water are placed in the flask and gently warmed.
The flame is then removed, and the mixture of alcohol and

FIG. 51.

sulphuric acid, which may be used warm, is slowly added from
the tap-funnel. The flask is occasionally shaken. A consider-
able rise of temperature occurs and the liquid darkens, whilst
aldehyde, with a little water and alcohol, distils. When the
mixture has all been added, the flask is heated on the sand-bath
until all the aldehyde has distilled (about 150 c.c.), which may
be determined by removing the cork from the flask and noticing
if the smell of aldehyde is still perceptible. The distillate is now
redistilled on the water-bath in the apparatus shown in Fig. 51.
COHEN'S ADV. P. o. c.                                                F